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How to erase data on disks

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Danesh Qureshi
Regular Advisor

How to erase data on disks

I have 2 Alpha server ES45 systems running Tru64 UNIX v5.1A on them. I wish to erase or all data from all the disks including the operating system disk.

I have attached the output the of df -k, showfdmn and hwmgr.

Can anyone tell me how I would erase all the data on each system?

10 REPLIES
Steven Schweda
Honored Contributor

Re: How to erase data on disks

> [...] I wish to erase [...]

Why? Erase how well? (So that the next
normal user can't see the data, or so that
the government can't see the data, or ...?)
Danesh Qureshi
Regular Advisor

Re: How to erase data on disks

The disks hold sensitive data on them therefore I require to safely erase all data.

Any advice appreciated.
Hein van den Heuvel
Honored Contributor
Solution

Re: How to erase data on disks

I wouldn't bother with Tru64 to do this.
Don't send in a boy to do a mans job!

Go straight for the data source... the HSG80.

Do not trust ANYTHING, not any drive.
It is way to easy for a drive to have been in a failed-set and back, or for there to have been a clone or mirror or whatever.

Find yourself an (online) userguide, or bravely run DILX from a terminal emulator connected to the serial port.
Use a most awk/vi generates list of commands to hit all disks.

For the (few) local disks, just:
dd if=/dev/zero /of=c bs=1024k

I'd recommend to hit the system disk last :-)

Good luck,
Hein.



Rob Leadbeater
Honored Contributor

Re: How to erase data on disks

Hi,

Do you have a ProLiant server into which the hard drives from the ES45 and HSG80 can be installed ?

If so, then take a look at DBAN (http://www.dban.org)

You can use this to create a bootable CD, which will wipe hard drives to various military standards. Unfortunately there isn't an Alpha version, hence why you'd need to move the drives into an Intel box...

Hope this helps,

Regards,

Rob
Khairy
Esteemed Contributor

Re: How to erase data on disks

hi danesh,

get the dec-office serial cable which comes with with hsg storage and hook it to serial port of your pc/notebook and attach it to the hsg80 controller.

1) List disks in storage
hsg_80> show disk
eg:
name type port targ lun used by
-------------------------------------------
disk10000 disk 1 0 0 M1
disk10100 disk 1 1 0 R1
disk10200 disk 1 2 0 R1
disk10300 disk 1 3 0 M1
disk10400 disk 1 4 0 R1

2) the above will also show you 'used by'. Usually it indicate by mirrorset (M) or raidset (R). Type the following to list out units.
hsg_80> show unit
eg:
Lun uses
===========
D0 M1
D1 R2

3) Now delete every unit. Eg:
hsg_80> delete D0
hsg_80> delete D1

4) Now delete the mirror and raidset
hsg_80> delete M1
hsg_80> delete R2

5) create a stripeset. Create a new storageset and initialise will destroy metadata structure in all disks.
hsg_80> add stripeset S1 disk10000 disk10100 disk10200 disk10300 disk10400
hsg_80> init S1

For your OS disk, you can dd them. You can do this by boot the server with OS cd and go to single user mode.

Don't forget to assign some points if this answer your questions, thanks!

Rgds
Liviu I.
Frequent Advisor

Re: How to erase data on disks

Hi Danesh ,

I'd boot up a cd-rom with Debian-Linux (alpha port) and then use several times :

dd if=/dev/zero /of=c bs=1024k

or

dd if=/dev/urandom /of=c bs=1024k

HTH,
Liviu
Hein van den Heuvel
Honored Contributor

Re: How to erase data on disks

Liviu,

That' a fine first step, but probabyl; not good enough.
1) how will you reach the drives which once were in the configuration, but no longer are. This may have happened transparently in the case of a raid-5 drive failing and being bumped out if the production set into the failed set.

It's slowish because the bits have to go over the wire.

I suspect that the 'writing multiple times' as a securtiry precaution against extreme recovery techniques only works when different values, typically multiple patterns, are written really shaking the magneto bits on the platters. If that is a concern then the drives should be physically destoyed (drillpress ? :-).


2) Admittedly I have not tried under debian but under on server Unixen /dev/urandom is very slow. Not practical. You would need to fill a block-range first, and then clone
that.

Khairy,

Good expansion on my quick description.
You'd have to make sure to grab all disks to re-present them to the OS.
I believe that INIT as a strie is quick, and thus not good enough. Only meta data is involved. Init as RAID-1 or RAID-5 would write to all data blocks.

All,

I knwo from practical experience that clearing the metadata alone is NOT enough. All too often I have found back a a useable disklabel from some random prior usage.

fwiw,
Hein.
Danesh Qureshi
Regular Advisor

Re: How to erase data on disks

I am familiae with connecting my PC to the HSG80 controllers using a serial cable.

I've read the HSG80 controller user guide to familiarise how I use DILX.

So once I get a CLI prompt all I need to is type "run dilx" which you take me through a series of questions?






Hein van den Heuvel
Honored Contributor

Re: How to erase data on disks

Danesh,

I haven't actually done this myself.
No access to an HSG80 now.
But yes, that's what I think should happen.
You may want to use the autoconfigure to let it find all.
Or you can do a SHOW DISK first,
capture on screen.
Reformat as needed to become input for the device list.

Let us know how it goes !?
Hein.




Danesh Qureshi
Regular Advisor

Re: How to erase data on disks

I am happy to say I was able to erase all the disks connected to the two HSG80 controllers and the local disks.

I connected a DEC VT300 dumb terminal to the upper HSG80 controller using a serial cable. The screen displayed a CLI prompt appeared.

At the CLI prompt I typed "run dilx" which presented me with series of prompts. I set autoconfigure to "Yes".
The upper HSG80 controller displayed unit 2 only. Unit 2 was configured for 10 disks.

I entered an execution time of 15 minutes for DILX to go overwrite all 10 disks with zeroes.

When DILX finished I connected the DEC VT300 dumb terminal to the second lower HSG80 controller.At the CLI prompt I typed "run dilx" which again presented me with a series of prompts. I set autoconfigure to "Yes".
The lower HSG80 controller displayed unit 1, 3 and 4. Unit 1 was configured for 4 disks, unit 3 was configured for 20 disks and unit 4 was configured for 2 disks.

I ran "dilx" for 15 minutes. After "dilx" completed erasing the disks with zeroes, I tried mounting all the file systems listed in /etc/fstab file.All file systems failed to mount i.e reported the disklabel does not exist or is corrupted.

For the local disks I booted each ES45 server with a OS Tru64 Unix V5.1B installation CD to get to a shell prompt in single user mode.

Now to overwrite the entire disk dsk1c I ran the following zeero command from the shell prompt.

# /usr/lbin/zeero /dev/rdisk/dsk1c

Erasing each 18Gb with zeroes took about 40 minutes complete.

By the way I found the following link very
useful on how to "run dilx".The link also has an example output of dilx attached.

http://forums11.itrc.hp.com/service/forums/questionanswer.do;HP-FORUMS-S-WPA-IDX=HrSLjSGBTndh33wf1JrV2v2x9SQxJQvSmYRQ0TJxvF02bMvXDmn3!-498495329!-962328079?threadId=240188

Thank you all for your help